In order to stably operate the grid, a supply and demand balance control which adjusts a balance between generated power supplied to the grid and load power consumed in the grid is important.
Conventionally, a supply and demand balance control service for the grid is provided using a power generator such as a gas turbine or a gas engine. Recently, consideration is being given to providing the supply and demand control service using a storage battery having a fast response speed to a relatively fast output change and load change of the grid.
In the supply and demand balance control using a power generator, power outputted to the grid is increased or decreased based on a supply power amount traded in the wholesale power market. Conversely, in the supply and demand balance control using a storage battery, a power amount to be supplied to the grid is controlled by charge and discharge of the storage battery. In the case where the supply and demand balance is controlled using a storage battery, charge cannot be performed when a state of charge in the storage battery (hereinafter referred to as SOC) reaches 100% of the storage battery capacity, and discharge cannot be performed when the SOC of the storage battery reaches 0%. In view of this, the SOC needs to be maintained at an appropriate level such that the storage battery avoids being in this state.
For example, Patent Literature 1 discloses a storage battery control apparatus which maintains the SOC of the storage battery used in the supply and demand balance control.